Grid loop Problem not solved

Hi,

i am working on my blog but still there is no improvement by me.

cause there is a Grid loop css.
i want to display 3 blocks per row by grid post layout but when i make width 33% then the 4th post goes in new row.
after that at a new line new 3 post starts. i want it continues.

for now i set the width 25% so they looks well.
and
i am failed to set the same box size for all the post boxes they change their height as per the quantity of text .

i am noob in css. plase give me working solution for it.

Thanks.

My Custom CSS Code :

#main{padding-left: 0px; !important;
padding-right: 0px; !important;}
.vantage-grid-loop article .excerpt p { display: none; }
/* Grid Layout for Homepage */
.vantage-grid-loop article {
float: left;
width: 21%;
padding: 0 7px;
margin-bottom: 5px;
-ms-box-sizing: border-box;
-moz-box-sizing: border-box;
-webkit-box-sizing: border-box;
box-sizing: border-box;
border-bottom: none;
}
.vantage-grid-loop article .grid-thumbnail {
display: block;
padding: 1px;
border: 1px solid #c2c5ca;
-webkit-box-shadow: 0 0 4px rgba(0,0,0,0.1);
-moz-box-shadow: 0 0 4px rgba(0,0,0,0.1);
box-shadow: 0 0 4px rgba(0,0,0,0.1);
background: #FFFFFF;
margin-bottom: -1px;
}
.vantage-grid-loop article h3 a {
  color: #00BFFF;           /* inherit */
  text-decoration: none;
  font-size: 20px;
  font-weight: normal;
  margin-bottom: 1px;
  display: block;
padding: 5px;
border: 1px solid #c2c5ca;
-webkit-box-shadow: 0 0 4px rgba(0,0,0,0.1);
-moz-box-shadow: 0 0 4px rgba(0,0,0,0.1);
box-shadow: 0 0 4px rgba(0,0,0,0.1);
background: #191919;
margin-bottom: 10px;
}
#primary {
  float: left;
  width: 80%;
}
body.no-sidebar #primary {
  float: none;
  width: 100%;
}
.page-template-default #primary {
  float: left;
  width: 80%;
}
/* Vantage Sidebar Background Color */
#secondary {
background: #fbfbfb;
padding: 2%;
width: 20%;
}
/* Vantage Sidebar Widget Headings Color */
#secondary .widget .widget-title {
color: #3b3b3b;
}
article.post.post-with-thumbnail-icon .entry-main,
article.page.post-with-thumbnail-icon .entry-main {
  width: 750px;
  width: 89.41%;
  /* 650px in standard width */
  float: right;
}

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